Beam Load Calculator
Bending moment and deflection for a beam.
Enter your values
Enter the uniform load in kN/m.
Enter the span in m.
Enter the young's modulus in GPa.
Enter the second moment of area in cm⁴.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Max bending moment
- 14.06 kNm
- Max shear
- 11.25 kN
- Max deflection
- 2.15 mm
- Span/deflection ratio
- L/2,321
Quick answer
A simply supported beam under uniform load has maximum moment at midspan equal to wL²/8.
M = wL² ÷ 8
At a glance
| What it does | Bending moment and deflection for a beam. |
|---|---|
| Category | Engineering |
| Inputs needed | Uniform load, Span, Young's modulus, Second moment of area |
| Main output | Max bending moment |
| Formula | M = wL² ÷ 8 |
| Cost | Free — no sign-up, no download |
How to use the Beam Load Calculator
- 1Enter the uniform load per metre.
- 2Enter the clear span.
- 3Enter the beam's E and I values from the section table.
Inputs explained
- Uniform load(kN/m)
- Enter the uniform load in kN/m.
- Span(m)
- Enter the span in m.
- Young's modulus(GPa)
- Enter the young's modulus in GPa.
- Second moment of area(cm⁴)
- Enter the second moment of area in cm⁴.
Worked example
Using the values the calculator loads with:
Inputs
- Uniform load4.5 kN/m
- Span5 m
- Young's modulus200 GPa
- Second moment of area8500 cm⁴
Results
- Max bending moment14.06 kNm
- Max shear11.25 kN
- Max deflection2.15 mm
- Span/deflection ratioL/2,321
Frequently asked questions
What deflection is acceptable?
L/250 for general use, L/360 under plaster ceilings.
Is this a design tool?
It is an estimate — structural work needs a qualified engineer.
What do I need to enter into the Beam Load Calculator?
Just 4 values: uniform load, span, young's modulus, second moment of area. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Beam Load Calculator work out the answer?
A simply supported beam under uniform load has maximum moment at midspan equal to wL²/8. It applies the formula M = wL² ÷ 8 and shows the working so you can check each step by hand.
Is the Beam Load Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.